requestdriven

Requestdriven, in information systems and software design, describes a paradigm where computation and data retrieval are initiated in direct response to explicit requests from a client or user. In a request-driven model, work is performed only because a valid request arrives, and systems return results or trigger follow-up actions as a consequence of that request. This contrasts with event-driven or push-based architectures, where components react to external events or streams even without a direct client request.

The concept applies across contexts such as API design, databases, and user interfaces. Web services commonly exemplify request-driven behavior: HTTP requests drive resource retrieval, state changes, and command execution. Databases inherently operate in a request-driven manner, executing queries and returning results only when asked. Even user interfaces can embody request-driven principles when UI actions correspond to specific user requests that fetch or compute data.

Key characteristics include a focus on per-request processing, often accompanied by statelessness to improve scalability and ease of caching. Security boundaries tend to be clearer when each request is independently authenticated and authorized. While asynchronous variants exist—where a client submits a request and later receives a result or a notification—the fundamental driver remains the explicit client request.

Benefits of request-driven design include predictable resource usage, simpler caching strategies for repeated requests, and easier reasoning about correctness. Trade-offs include potential latency due to round-trip communication and the possibility of underutilization during low request rates. Related concepts include event-driven and demand-driven approaches, which emphasize work triggered by external events or data demand rather than direct client requests.